Lucalox XO Superlife lamps comprise a sodium discharge system operating at a high pressure within a ceramic arc tube which is mounted in an outer glass bulb. These lamps offer outstanding luminous efficacy, lumen maintenance thus reducing energy and maintenance costs. All lamps have two arc tubes. The second arc tube will instantly light after a momentary power interruption. Arc tubes are Monolithic construction for 50-400W lamps. Easy replacement of standard HPS lamps, fits standard HPS sockets – no new wiring, ballast or fixture are required. Light BulbsGBP125372